Vegetation Ecosystem Studies on both hill and wetland species, Great Barrier Island, New Zealand

 

Liu Huan (2015). Vegetation Ecosystem Studies on both hill and wetland species, Great Barrier Island, New Zealand. Journal of Environment and Health Science (ISSN 2314-1628). 2015 (09). https://doi.org/10.58473/JEHS0011

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Article 9. Vegetation Ecosystem Studies on both hill and wetland species, Great Barrier Island, New Zealand.

Author: Liu Huan (1983-), Master of Science (First Class Honours, 2009), The University of Auckland. ORCID: https://orcid.org/0000-0003-4881-8509

Advisor: George Perry, School of Environment, Faculty of Science, The University of Auckland

Formally published on 09/04/2015; Latest revised on 09/06/2023.

Abstract
This field study attempts to identify the community structure by a combination of classification and ordination methods based on the sampling data of vegetation species in Little Windy Hill, Great Barrier Island, New Zealand. Three distinct vegetation community units have been identified. Unit1 mainly includes dense stands of old Coporosma arborea species with a mean canopy height of 9m and a mean basal area of 78.95m/ha, while there are mainly four dominated species in unit 2, including Beilschmiedia tarairi, Coprosma arborea, Dysoxylum spectabile, and Rhopalostylis sapida. Unit 2 has the largest basal area of 90.8m/ha. Unit 3 comprises a large proportion of kanuka (Kunzea ercoides) and a few Manuka (Leptospermum scoparium) stands with the least basal area of 39.46m/ha and a mean canopy height of 11m. The succession pattern of these vegetation units are from unit 3 → unit 1 → unit 2. The environmental gradients underlying the temporal and spatial dynamics of community succession are associated with slope, topographical unit, aspect, soil conditions as well as historical disturbance, such as fire and grazing activities, which together explain the succession patterns of vegetation community. Another field sampling study has been also conducted in Great Barrier Island, but wetland species are selected to analyze the ecosystem community. This wetland field study examines the community-unit and individualistic concepts by using environmental gradient analysis of vegetation distribution patterns in Kaitoke swamp, Great Barrier Island, New Zealand. Both water depth and transect line are chosen as environmental gradients, along with which the vegetation communities show similar distribution patterns. The boundaries of vegetation species distribution tend to be clustered within some specific intervals of environmental gradient. Nevertheless, no correlation has been found between upper and lower boundaries along both gradients. This conclusion supports neither community-unit nor individualistic conception, which indicates that other hypotheses regarding to community distribution patterns would suit better for the studied ecosystem, e.g. ecological niche which is further discussed in this paper for restoration of wetlands. However, there are some limitations in the sampling accuracy supporting these classic ecological theories.

Key words: Community Classification; Community Succession; Environmental Gradient Analysis; Community-unit; Individualistic concepts.

新西兰大坝岛山地和湿地植被生态系统研究

摘要：此项野外调研旨在应用多元聚类分析方法辨认新西兰大坝岛小风山的植物群落的结构。三个明显的植物群落在研究中被分类出并且确认。群落单元一的建群种主要包括Coporosma arborea 的古树，拥有平均9m的树冠层高度和平均78.95m/ha的树干面积。单元二主要有四个优势种，分别是Beilschmiedia tarairi, Coprosma arborea, Dysoxylum spectabile, and Rhopalostylis sapida.单元二拥有最大的平均树干面积，达到了90.8m/ha。单元三的优势种群主要是由kanuka (Kunzea ercoides)种群和Manuka (Leptospermum scoparium)种群组成的，平均树干面积只有39.46m/ha，是三个群落单元中最小的，然而平均树冠层高度则达到了11米。决定该植物群落时空演替规律的环境梯度主要与坡度，地型单元，向阳面，土壤条件，历史上人类干扰活动（如火灾和畜牧）等因素相关。群落演替的顺序为从单元三 →单元一 → 单元二。另一项实证型采样研究也在新西兰大坝岛开展，但是选取了湿地植被物种用于群落单元分析。这项实证性研究旨在应用环境梯度分析方法论证两个植物生态理论假设：“群落单元”和“独立单元”假设。采样地点为新西兰大坝岛卡托克沼泽。水深和离岸距离被选取为环境梯度的分析变量。沿着两个环境梯度变量，植被群落显示出了相似的分布形态。植被种类的分布边界趋向于在环境变量的某个特定值域集中。然而，沿着环境梯度变量，植被的上层和下层分布边界之间没有发现显著的相关性。这个结论既不支持“群落单元”假设，也不支持“独立单元”假设。其他关于植物生态分布的理论假设应当更适合于这个被研究的沼泽生态系统, 比如生态位理论在本文得到进一步论述并且应用于湿地修复。然而，采样方法的局限性也很可能使得此项研究的环境梯度分析达不到支持理论假设的精度。

关键词：群落分类; 群落演替; 环境梯度分析；“群落单元”假设；“独立单元”假设。